Rates and patterns of occupational mobility in Indianapolis during the 1850s are analyzed using data from manuscript federal census schedules. Between 1850 and 1860, nearly half the working males who remained in the city were mobile, most of them within the nonmanual or manual categories. Analysis by age cohorts revealed that the young were more likely to be upwardly mobile and less likely to be downwardly mobile than older cohorts of workers. This differential mobility was almost totally a result of the different origin distributions of the cohorts. An analysis of nativity-ethnicity indicated that immigrant males occupied favorable positions in the occupational hierarchy in 1850, which led to considerable upward mobility. Once structural conditions were taken into account, however, differences between the mobility rates of native-born and foreign-born were small, with the native-born somewhat more likely to cross the manual-nonmanual boundary. Basic findings from this study are compared with those from studies of Boston, Philadelphia, and Houston.